A touch panel is an input apparatus through which one moves a cursor or inputs an instruction by means of sliding or clicking operations with a touch object such as a finger. For a capacitive touch panel, capacitance would be changed when a user's finger gets close to the touch panel. The change in the capacitance is detected by the touch panel itself and converted into coordinates, such that movements of the finger are derived and converted into corresponding control commands.
Traditional capacitive touch sensors typically have a two-layered structure (i.e., a layer of driving electrodes Tx and a layer of sensing electrodes Rx), resulting in high cost. Recently, a solution of a touch screen using monolayer sensors has been proposed. The typical structure of the monolayer sensors is as shown in FIG. 1. A plurality of sensing electrodes, a plurality of driving electrodes, a plurality of first connecting lines and a plurality of second connecting lines are included in the same conductive layer. The plurality of sensing electrodes 10, 12 and 14 are connected to respective sensing electrode signal input terminals via the first connecting lines R1, R2 and R3, respectively. The driving electrodes are arranged between adjacent sensing electrodes 10, 12 and 14, and each column of driving electrodes includes a plurality of driving electrodes 20. In this example, each column of driving electrodes includes eight driving electrodes 20, each of which is connected to a respective driving signal input terminal via a respective one of second connecting lines T1, T2, T3 . . . T8. Each driving electrode and a portion of a corresponding sensing electrode constitute a capacitor 30, as shown by the dashed box in FIG. 1. When touch occurs in a region corresponding to the capacitor 30, the capacitance would be changed, and then a touch control signal is detected within the region. With each capacitor being a detection point, the number of detection points depends on the number of driving electrodes in each column of driving electrodes.
With the increased size of the display panel and the improved touch control resolution, it is required to not only increase the number of sensing electrodes and driving electrodes in the entire panel region, but also increase the number of sensing electrodes and driving electrodes in a unit area. However, further improvement of the touch control resolution is limited in the existing design. For example, as the number of electrodes increases, more second connecting lines are needed to transmit driving signals thereto, which causes more difficulties in wiring and design of driver chips and results in an oversized flexible print circuit (FPC) that is to be bonded.
Accordingly, there is a need for an improved touch input device and a touch display device using the same.